Vehicles which run on internal combustion engines using gasoline or diesel oil as their fuel produce severe environmental pollution, such as air pollution. Thus, recently, to reduce environmental pollution, development of electric vehicles or hybrid electric vehicles has become more active. Cells are the power sources of such electric and hybrid vehicles. High-power secondary cells using nonaqueous electrolytes having high energy density were recently developed. Further, high-capacity high-voltage batteries which comprise high-power secondary cells connected in series are generally used in machines, such as motors of electric vehicles or the like, which need high power.
Typically, a single high-capacity high-voltage battery includes a plurality of secondary cells which are connected to each other in series. Furthermore, the high-voltage battery further includes a BMS (battery management system). The BMS will be briefly explained below. In the case of such a battery, in particular, a battery for an HEV (hybrid electric vehicle), from several to several tens of secondary cells alternately perform charging and discharging. Hence, management of the battery including the operation of controlling such charging and discharging is required so that the battery is maintained in a state of optimal operation. For this, the BMS for controlling the general conditions of the battery is used. Such a BMS senses the voltage, current, temperature, etc. of the battery, determines a current SOC (state of charge) of the battery, and controls the SOC to keep the fuel efficiency of the vehicle at its maximum.
As mentioned above, the high-voltage battery includes the cells, a connection structure for connecting the cells to each other, and the BMS connected to the connection structure.
FIGS. 1 and 2 illustrate a connection structure of a conventional high-voltage battery. This conventional high-voltage battery includes a plurality of cells which are connected to each other in series. In this conventional art, as shown in FIGS. 1 and 2, upper connection members and lower connection members are used to mechanically and electrically connect the tabs of the cells to each other. The tab of each cell is disposed between the corresponding upper and lower connection members. In detail, after the tab of each cell is disposed between the upper connection member and the lower connection member, a bolt attached to the lower connection member passes through a hole of the upper connection member and is tightened with a nut above the upper connection member. Thereby, the cells are mechanically and electrically connected to each other.
However, in the conventional connection structure of the high-voltage battery, a large number of connection units corresponding to the number of the tabs of the cells are required. Furthermore, each connection unit itself includes a plurality of parts. Thus, due to an increased number of parts, the production cost increases, and the process of assembling the parts is complicated. Moreover, such a complex connection structure makes the entire system complex. In addition, due to the large number of parts, the volume of the connection structure increases, thus increasing the entire volume of the high-voltage battery.